Estimate your one rep max using the Epley formula from the weight lifted and reps completed in a submaximal set.
The Epley formula is one of the most common ways to estimate a one-rep max from a submaximal set.
Instead of testing a true max, you can use a moderate rep set to build a working estimate for percentage-based programming. Epley is widely used because it is simple and tends to work reasonably well in lower to moderate rep ranges.
This calculator applies the formula, generates a percentage chart, and shows corresponding training weights.
It is useful when you want percentage-based training weights without taking a maximal attempt. The estimate is best treated as a programming reference, especially when the source set is kept in a moderate rep range.
Epley Formula: 1RM = weight × (1 + reps / 30) Example: 225 lbs × (1 + 5/30) = 225 × 1.167 = 262.5 lbs Accuracy: Best for 2–10 reps. Tends to overestimate above 10 reps. For 1 rep input, 1RM = weight lifted (no formula needed).
Result: Estimated 1RM: 262.5 lbs
Lifting 225 lbs for 5 reps gives: 225 × (1 + 5/30) = 225 × 1.1667 = 262.5 lbs. This means your training percentages would be: 90% = 236 lbs, 80% = 210 lbs, 70% = 184 lbs, 60% = 158 lbs. These percentages help you plan sets across different training goals — strength (85–95%), hypertrophy (65–80%), and endurance (50–65%).
Boyd Epley developed his formula while serving as strength coach at the University of Nebraska in the 1980s. He needed a practical way to set training weights for football players without the time and injury risk of constant maximal testing. The formula's simplicity (just multiply by 1 + reps/30) made it easy for coaches to calculate on the fly, even without a calculator.
Retest every 4–6 weeks during a linear progression program, or at the start of each new training block in a periodized program. If your training weights feel significantly easier or harder than prescribed RPE, your estimated max may have shifted and should be retested. Avoid retesting during deload weeks or when fatigued from high-volume training.
The percentage chart is a simple reference for setting loads. For powerlifting peaking: work from 70% up to 95–100% over 8–12 weeks. For bodybuilding: stay primarily at 65–80% with higher volume. For athletic performance: use 75–85% with explosive intent. Treat the chart as a starting framework and adjust based on actual performance.
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This worksheet applies the Epley equation to a submaximal set and treats the output as an estimate rather than a literal tested max.
Studies show the Epley formula is typically within 5–10% of actual 1RM for trained individuals in the 2–10 rep range. Accuracy decreases above 10 reps, where it tends to overestimate. Individual variation exists — some people's rep-max relationship is naturally different from the formula's prediction.
At high reps (12+), fatigue increasingly becomes a cardiovascular and muscular endurance challenge rather than a pure strength limitation. The Epley formula assumes a linear relationship between reps and max strength, but at higher reps, other factors (lactic acid, glycogen depletion, mental fatigue) limit performance before true maximal strength is reached.
For 1–6 reps, both formulas give very similar results. For 7–10 reps, Brzycki tends to give slightly lower (more conservative) estimates. Most coaches recommend using the average of multiple formulas for the best accuracy. Our multi-formula calculator does this automatically.
The formula works best for compound barbell movements (bench press, squat, deadlift, overhead press). It's less accurate for isolation exercises, machine movements, and exercises with variable resistance. It was originally developed and validated for barbell exercises.
Common programming guidelines: Strength — 3–5 reps at 85–95% 1RM. Hypertrophy — 6–12 reps at 65–80% 1RM. Muscular endurance — 12–20 reps at 50–65% 1RM. Power — 1–3 reps at 80–90% 1RM with explosive tempo. These are starting points; adjust based on individual response.
You should go close to failure (within 1–2 reps of failure, called RPE 8–9) but not to absolute technical failure. Stopping 1 rep short gives a very similar estimate while being safer. If you stop 2–3 reps before failure, you'll underestimate your 1RM.